Viral and Mosquito Borne

Question 1

Influenza

Answer 1

-the flu
-causative: influenza A and B virus
-reservoir- humans
-incubation- 1-4 days, average 2
-worldwide
-most common in temperature climates during winter
-spreads via respiratory droplets
-causes periodic epidemic, has potential to cause global pandemics
-pandemic occurs when new strain emerges for which humans have had little to no previous exposure
-acute, febrile viral respiratory tract infection
-3 types (A-C) based on core protein -> only A and B cause significant disease
-type A are further classified based on 2 specific antigens, hemagglutinin (HA or H) and neuraminidase (NA or N), found on the surface of the virus
-antigens are responsible for HN classification often seen on annual vaccines
-constantly undergo genetic changes via antigenic drift (frequent and minor) and antigenic shift (infrequent and significant), new and updated vaccinations are required each year

Question 2

Influenza clinical diagnosis

Answer 2

-acute fever, chills, rigors, malaise, myalgia, headache, rhinorrhea, nonproductive cough
-nausea, vomiting, diarrhea may occur in some pts -> mostly children
-immunocompromised, extremes of age, pregnant women, residents of long term care facilities, and those with preexisting medical conditions are more likely to have severe disease and complications
-pneumonia (from influenza directly or secondarily from bacteria) is a potential complication

Question 3

influenza treatment

Answer 3

-rapid influenza dx test (RIDT) are immunoassays that detect influenza A and B viral antigens
-nasopharyngeal swabs tested for using polymerase chain reaction (PCR)
-2 classes of drugs to treat: adamantanes include amantadine and rimantadine -> target and inhibit function of the M2 protein and are only effective against influenza A
-increased resistance to these drugs over years and efficacy against both influenza A and B -> neuraminidase inhibitors are preferred for treatment and prophylaxis
-neuraminidase inhibitors include oseltamivir, zanamivir, and peramivir
-oseltamivir is taken orally and zanamivir is inhaled powder
-newer drug -> peramivir -> indicated for treatment only (not prophylaxis) and is given as single intravenous dose
-medications are thought to decrease duration and severity of illness and are only effective when initiated within 48 hours of symptoms onset

Question 4

rubeola

Answer 4

-causative agent- Measles virus (MV)
-incubation- 7-21 days, average 10-14 days
-worldwide
-highly contagious
-vaccine preventable
-high fever, cough, coryza, conjunctivitis followed by maculopapular rash

Question 5

rubeola signs and symptoms

Answer 5

-following 7-21 day incubation:
-prodromal symptoms- high fever, malaise, conjunctivitis, coryza (runny nose), and cough
-koplik spots: small white to gray spots on the buccal mucosa opposite the lower molars (grains of salt on a red background)
-pathognomonic and may appear 2-3 days before viral exanthem
-after 3-4 days (range (1-7 days) of prodromal symptoms -> pts enter the EXANTHEM phase of the disease, characterized by the development of a red, maculopapular rash that starts at the head and proceeds in cephalocaudal and outward progression
-rash persists for up to 7 days and fades in same order it appeared
-as rash resolves, pt enter RECOVERY phase and may continue to have mild cough for 1-2 weeks
-complications of measles- diarrhea, otitis media, pneumonia, encephalitis, seizures, and death
-infection confirms lifelong immunity

Question 6

rubeola dx and treatment

Answer 6

-serum IgM and IgG levels can be checked
-IgM is elevated in acute phase and remain elevated for 1-2 months
-PCR can be used to detect the MV in serum, urine, oropharyngeal and nasopharyngeal secretions
-treatment is supportive
-preventable by vaccine
-koplikl spots are temporary viral enanthem and are pathognomonic for measles
-fever is high grade and tends to last for 4 days and occurs concurrently with conjunctivitis, coryza, and cough
-subacute sclerosing panencephalitis is rare and fatal degenerative disease of CNS that occurs in some pts 7-10 years about initial infection

Question 7

Mumps

Answer 7

-aka epidemic parotitis
-causative agent- mumps virus
-incubation- 12-25 days, average 16-18 days
-worldwide
-peak incidence- late winter-early spring, sporadic outbreaks
-vaccine preventable
-known to cause parotitis
-reproduces in upper respiratory tract
-spreads via saliva, oropharyngeal secretions, and respiratory droplets
-contagious and should be isolated with droplet precautions for at least 5 days after onset of parotitis

Question 8

mumps signs and symptoms

Answer 8

-after 12-25 day incubation:
-prodromal symptoms including low grade fever, headache, malaise, fatigue, myalgia, followed by parotitis
-parotid swelling often bilateral (75%) and progressed over next 72 hours
-glands remain swollen for about 1 week
-complications: orchitis, oophoritis (ovarian inflammation), infertility, pancreatitis, meningitis, and/or deafness

Question 9

mumps dx and treatment

Answer 9

-most cases are self limiting
-dx is based on hx and clinical presentation
-serology can reveal acute rise of IgM or fourfold rise of IgG in convalescence phase
-IgG of no value is previously vaccinated pts
-serum and buccal/oral swabs can be tested for mumps using PCR
-treatment is mostly supportive
-vaccination is best way to prevent

Question 9

rubella

Answer 9

-aka german measles, 3 day measles
-causative agent- rubella virus
-incubation- 12-23 days, average 14 days
-worldwide
-contagious
-vaccine preventable
-low grade fever, lymphadenopathy
-mild 3 day maculopapular rash

Question 9

rubella signs and symptoms

Answer 9

-many cases are asymptomatic
-children exhibit milder disease than adult
-following 12-23 incubation: pts develop low grade fever, lymphadenopathy, and mild maculopapular rash that proceeds in cephalocaudal and outward progression
-lymphadenopathy tends to affect posterior auricular, suboccipital, and posterior lymph nodes
-fever and lymphadenopathy may precede the rash by a few days or occur concurrently
-rash is fainter than in measles and last about 3 days, hence the term 3 days measles
-headache, malaise, conjunctivitis, coryza, and cough may occur as part of prodrome, more commonly in older pts
-up to 70% of adolescents and adult females develop arthralgia and arthritis that may persist for several months
-complications are more common in older pts and may include thrombocytopenic purpura and encephalitis
-rubella during pregnancy- specifically first trimester -> can cause stillbirth or birth defects
-congenital rubella syndrome causes cataracts, heart defects, and deafness

Question 10

rubella dx and treatment

Answer 10

-serum IgM and IgG levels can be obtained
-IgM will be elevated in acute phase of illness, and fourfold rise in IgG in convalescence will confirm recent infection
-PCR testing can be performed on oropharyngeal or nasopharyngeal swabs and urine
-obtaining samples from both sources will increase the likelihood of detecting the virus
-treatment is supportive and is prevented by vaccine

Question 11

rubella vs measles

Answer 11

-similar but have some distinct differences
-rubella is characterized by low grade fever, lymphadenopathy, and rash
-measles is characterized by high grade fever, cough, coryza, conjunctivitis and rash
-rash in rubella is fainter (pink vs red) and lasts for shorter duration (3 days vs 7 days)
-rubella is milder disease but can cause congenital defects in pregnancy
-forchheimer spots are transient erythematous petechiae seen as enanthem on hard palate in about 20% of pts with rubella
-since these spots can also be seen in measles and scarlet fever -> they are not pathognomonic for rubella
-Koplik spots- small white to gray spots on buccal surface opposite the lower molars, are pathognomonic enanthem for measles

Question 12

Rabies

Answer 12

-aka hydrophobia
-causative agent- rabies virus
-reservoirs- bats, racoons, skunks, foxes in US, dogs in developing nations
-incubation- 1-3 months mostly, onset can be delayed for years
-worldwide- highest incidence in Asia and Africa

Question 13

Rabies signs and symptoms

Answer 13

-prodromal symptoms- fever, headache, malaise, nausea, vomiting, and pain or paresthesia at the site of bite
-when virus spreads to CNS -> pts will exhibit 1 of 2 clinical presentations of the disease
-furious rabies- most common presentation (70%) and includes classic findings of hydrophobia, insomnia, confusion, paranoia, anxiety, agitation, and hallucinations progressing to coma and death
-paralytic rabies- presents in 30% of pts and is associated with an ascending flaccid paralysis, fever, confusion, coma, and death

Question 14

rabies testing

Answer 14

-fatal viral zoonosis transmitted form saliva or infected animals to humans
-after relatively long incudbation period- pts develop encephalopathy followed by death
-2 presentations- encephalopathic (furious rabies) OR paralytic (dumb rabies)
-encephalopathic rabies is classic and more common presentation, notable for hydrophobia (fear of water) and spasms of the pharynx that occur when pts attempts to drink water
-testing- direct immunofluorescent staining of skin biopsy and/or detection of anti-rabies virus antibodies in serum or cerebral spinal fluid (CSF)

Question 15

rabies treatment

Answer 15

-supportive
-most pts die within 10 days of onset of coma
-vaccination series to prevent rabies given either a preexposure or postexposure prophylaxis
-preexposure vaccinations are given on days 0, 7, and 21 or 28 and are recommended for veterinarians, rabies researchers, and some travelers
-postexposure vaccinations are given on days 0, 3, 7, and 14 with immunocompromised pts getting a 5th dose on day 28
-in addition to vaccine- postexposure prophylaxis includes weight based rabies immune globulin on day 0, with half the dose administered as close to wound as possible
-those who have received preexposure vaccination series do not need immune globulin and should be given booster shots of vaccine at days 0 and 3
-proper handwashing and cleaning of any bite wounds with iodine can help reduce transmission of rabies

Question 16

Fifth’s disease

Answer 16

-aka- slap face, slapped cheek syndrome
-causative agent- parvovirus B19
-incubation- 4-14 days
-worldwide
-late winter- early spring, peak incidence is in children 5-15 years old
-erythema infectiosum (EI)- self limiting febrile viral illness that produces characteristic slapped cheek facial rash followed by lace-like reticular rash on trunk and extremities
-pts most infectious prior to development of rash

Question 17

5ths disease symptoms

Answer 17

-after 4-14 day incubation period -> prodrome of low grade fever, malaise, headache, and rhinorrhea
-after 2-5 days slapped cheek facial rash develops followed 1-4 days later by lacelike reticular rash on trunk and extremities
-rash can be pruritic, worsens with sunlight and spares the palms and soles
-rash typically lasts for 5-10 days and may periodically return with exposure to sunlight, heat, exertion, or stress
-older children adolescents, and adults particularly females, may develop mild polyarthritis of the hands, wrists, ankles, and knees that can last for several weeks or become chronic in some pts

Question 18

5ths disease testing and treatment

Answer 18

-EI dx based on hx and clinical presentation
-IgM/IgG serology and nuclei acid detection can be performed but should be reserved for pregnant women with known exposure (risk of congenital defect) and immunocompromised pts
-treatment- supportive, ibuprofen or acetaminophen as needed for fever, myalgia, arthralgia

Question 19

dengue

Answer 19

-aka dengue hemorrhagic fever, breakbone fever
-causative agent- dengue fever virus (DENV)- 4 major serotypes
-vector- Aedes spp.- A. aegypti is the prinicpal vector, but A. albopictus and A. polynesiensis can also transmit the virus -> these are all daytime feeding mosquitos
-reservoir- human and non human primates -> monkeys in West Africa and Southeat Asia
-incubation- 3-14 days
-tropical and subtropical regions are at risk and regions that may support Aedes spp. mosquito
-acute febrile mosquito borne viral illness

Question 20

dengue signs and symptoms

Answer 20

-Denguefever (DF) - acute febrile illness -> retroorbital headache, malaise, severe myalgia, arthralgia, and rash
-most often asymptomatic or mild but can be severe and progress to hemorrhage (denguehemorrhagic fever [DHF]) or shock (dengueshock syndrome [DSS])
-initial infections often mild or asymptomatic
-subsequent infections tend to be worse
-DHF, a more-severe disease presentation, progresses through three phases:
-Febrile Phase
-Critical Phase
-Recovery Phase

Question 21

dengue febrile phase

Answer 21

fever, headache, myalgia, arthralgia, rash, petechiae, easy bruisability, epistaxis, mucosal bleeding, and a positive tourniquet test
-Children often present with nausea and vomiting
-symptoms are similar to DF

Question 22

dengue critical phase

Answer 22

gastrointestinal (GI) hemorrhage and plasma leakage into the chest and peritoneal cavities, occurring after the fever breaks.
-Abdominal pain, ascites, and dyspnea can occur. DSS can occur in this phase unless aggressive fluid resuscitation is initiated.

Question 23

dengue recovery phase

Answer 23

Patients will begin to feel better as capillary leakage stops and fluids begin to be reabsorbed. Bradycardia and a rash described as “white islands in a sea of red” may be observed.

Question 24

dengue dx and treatment

Answer 24

-labs- leukopenia, and thrombocytopenia
-hepatitis is common -> increased hematocrit and decreased albumin indicate capillary leakage and impending shock
-IgM and IgG serology and PCR testing is available
-fluids and blood products may be indicated if disease progresses to critical phase
-vaccines are currently being developed
-avoid mosquitos

Question 25

west nile virus

Answer 25

-causative- west nile virus (WNV)- flavivirdae
-vector- culex spp.
-region- global
-incubation- 2-14 days, average 2-6 days
-70-80% of infections are asymptomatic
-can develop fever, headache, fatigue, myalgia, arthralgia, transient maculopapular rash, nausea, vomiting
-progression to encephalitis occurs in <1% of symptomatic pts ->pts may develop polio-like acute flaccid paralysis
-mortality for neuroinvasive disease is about 30% and neurologic sequelae have been reported in up to 50% suriviors
-treatment is supportive

Question 26

zika virus

Answer 26

-causative agent- Zika virus (ZIKV)
-vectors- Aedes aegypti, Aedes albopictus
-reservoir- humans and non human primates
-incubation- 3-12 days
-Tropical and subtropical regions are at risk, as well as any regions that may support theAedesspp. mosquito. Most U.S. cases are in returning travelers; however, the Centers for Disease Control and Prevention (CDC) has confirmed several cases of local mosquito-borneZikain Florida and Texas.

Question 27

zika virus signs and symptoms

Answer 27

-Zikais an acute febrile mosquito-borne illness similar to but milder than dengue.
-Infection is characterized by fever, arthralgia, myalgia, headache, conjunctivitis, and a pruritic maculopapular rash that begins on the face and spreads to the rest of the body.
-Most patients (∼80%) are asymptomatic or have mild disease. When symptomatic, symptoms last for about 3–7 days.
-Zikainfections during pregnancy have been implicated in microcephaly and other fetal brain defects, with Brazil being hit the hardest.
-Guillian-Barré syndrome has also been reported following someZikainfections
-Often asymptomatic, but classic signs of infection include fever, arthralgia, conjunctivitis, and rash. The fever inZikais low grade, unlike the high fevers of dengue and chikungunya.

Question 28

chickungunya

Answer 28

-causative- chikungunya virus (CHIKV)
-vectors- Aedes spp.- speicifically A. aegypti and A. albopcitus
-reservoir-Human and nonhuman primates. The World Health Organization (WHO) reports that some nonprimates, birds, rodents, and small mammals may serve as reservoirs.
-incubation- 2-12 days, average 3-7
-Tropical and subtropical regions are high-risk areas, as well as any region that may support theAedesspp. mosquito. In late 2013, local transmission ofchikungunyawas identified in several Caribbean countries and territories. The disease has since spread to South America
-Chikungunyais an acute febrile mosquito-borne viral illness characterized by high fever and polyarthralgia

Question 29

chickungunya

Answer 29

-majority (80%) infected are symptomatic
-should be suspected if recent travel to endemic regions and presenting with high fever and polyarthralgia
-fever can be biphasic
-Arthralgia usually bilateral and symmetric, predominantly affecting the peripheral joints of the hands, feet, wrists, and ankles
-Knees, elbows, and shoulders can also be involved -> hips are often spared.
-Myalgia, headache, malaise, conjunctivitis, and nausea can occur.
-transient (3–4 day) maculopapular rash affecting face, trunk, extremities in 40%–50%
-Unlike dengue, hemorrhage is very rare.
-Guillian-Barré syndrome may occur as a post-infectious complication
-may develop chronic polyarthritis, with as many as 20% still complaining of arthralgia 1 year after the initial infection.

Question 30

Chikungunya dx and treatment

Answer 30

-serum tested for virus, viral nucleic acid, orchikungunya-specific IgM.
-virus can be detected for 3 days
-viral RNA for 8 days
-IgM should be elevated within 1 week of symptom onset
-IgG elevates within 2 weeks of infection.
-Since diseases have similar presentations, testing for Zika and dengue should also be considered
-Treatment: Avoid mosquitoes
-treatment is supportive